Attached file (in google calendar) produces error

When I set up an external calendar in typo3 (with a google calendar) and import that calendar everything works fine. But if i attach a file to one of the events in the google calendar (which typo3 then "downloads") an error occurs and no data can be fetched.

The error is "Oops, an error occured! Call to undefined method TYPO3\Cms\Core\Utility\BasicFileUtility::init()"